The present invention relates to decorrelation of audio signals. Decorrelation is an audio processing technique that reduces the correlation between a set of audio signals. Decorrelation may be used to modify the perceived spatial imagery of an audio signal. Examples of how decorrelation may be used to modify spatial imagery include: decreasing the “phantom” source effect between a pair of audio channels; widening the perceived distance between a pair of audio channels; improving the externalization of an audio signal when it is reproduced over headphones; and/or increasing the perceived diffuseness in a reproduced sound field.
A common method of reducing correlation between two (or more) audio signals is to randomize the phase of each audio signal. For example, two all-pass filters, each based upon different random phase calculations in the frequency domain, may be used to filter each audio signal. However, the decorrelation may introduce timbral changes or other unintended artifacts into the audio signals.